1. Field of the Invention
The present invention relates to a control device for a liquid crystal display (LCD) device, in particular, to an LCD device which is capable of preventing erroneous display that tends to be generated at the time of disconnecting the power supply.
2. Description of the Prior Art
A tendency exists in recent semiconductor devices to attempt to reduce the power consumption by stopping the feeding of power to the circuits that are not in operation.
For instance, among LCD devices for displaying desired content on the display unit, which receives the voltage necessary for driving the LCD from a boosting circuit that uses a capacitor and supplies the voltage to the LCD to be driven through operation of a plurality of switches, there are some that disconnect the power supply when there is no need to have a continued display of the content, inorder to reduce the power consumption.
However, in such an LCD device, discharge of a charged capacitor requires a certain length of time and the switches behave unstably due to temporary uncontrollability of the switches. Because of this, an LCD in the nonlighting condition is converted tot he lighting condition, for example, due to the residual voltage in the capacitor. Therefore, there arises an inconvenience in which there is temporarily displayed on the display unit a content which is different from what had been displayed before the power supply was disconnected. It means that there will be a problem, in particular when a display device or the like is constructed by using LCD. This is because when the power supply for the LCD is interrupted frequently, the above inconvenience will arise for each time the power supply is disconnected, giving displeasure to the use of the device.